The invention relates to an apparatus for the quasi-continuous treatment, especially for the coating, of tabular substrates supplied in cassettes, having a series of lock chambers and treatment chambers containing treatment apparatus, having a transport system for transporting at least one substrate holder through the chambers and a loading station for loading the substrate holder with a substrate from the cassette, and unloading a substrate from the substrate holder into the cassette.
The treatments can be any of a great variety for controlling the coating process and or the structure of the coating and/or the properties of the substrates. These treatments include not only coating process but also etching processes, as well as cleaning and heat treating processes and processes for the reactive after-treatment of coatings including controlled cooling processes.
The tabular substrates can be circular, discoidal such as CD disks and magnetic disks, approximately circular disks such as wafers, or even rectangular or square plates such as are required for many other optical and/or electronic purposes. The apparatus, however, is preferentially suitable for substrates in plate form whose outline corresponds more or less to a circle.
Quasi-continuous treatment is a treatment in which the substrates enter step by step into the apparatus through a lock and leave it again through a lock, but uninterruptedly as far as the end result is concerned. Any temporary stopping is caused as a rule by the lock chambers and/or by stopping during the individual steps of the treatment.
It is known to supply tabular substrates, such as wafers for example, in cassettes which are equipped with holders to maintain spaces between the individual substrates. These holders also put the principal or central planes of the individual substrates in a vertical position. It has proven difficult, however, to take the substrates singly out of the cassettes and insert them in substrate holders when the substrates are to be transported through the apparatus in a vertical position. For this purpose the substrate holder must be provided with holding or catch means to prevent the substrates from falling out of the holder. This placed a great limitation on the use of automatic manipulators.
The invention therefore is addressed to the problem of improving an apparatus of the kind described above so that it can be loaded with substrates and the substrates can be unloaded again by means of a simple and reliably operating automatic loading station on the running conveyor belt, without the need for holding the substrates in all spatial coordinates in form-fitting mountings and without the risk of their falling out of the substrate holders.